1. Field of the Invention
The present invention relates to a film cartridge loader for a camera. More particularly, this invention is concerned with a film cartridge loader for a camera using a film cartridge. In the film cartridge, a rolled film is stowed. The film cartridge has an interceptive door at the film entrance and exit.
2. Description of the Related Art
In recent years, a novel camera system has generally been adopted in practice for cameras designed for photography or the like. The novel camera system uses a 24 mm wide film that is rolled and stowed in a compact film cartridge.
The film cartridge which is compatible with the novel camera system includes a spool shaft supported so as to be able to freely rotate. A length of film is wound about the spool shaft up to the distal end of the film, whereby the rolled film is stowed in the film cartridge. By rotating the spool shaft, the film is fed from the cartridge or rewound into the cartridge.
The film cartridge has an opening serving as a film entrance and exit. The opening has an interceptive door for preventing invasion of extraneous light into the interior of the film cartridge through the opening. In a normal state, the interceptive door is closed to keep light out of the interior of the film cartridge. For feeding or rewinding the film, the interceptive door is opened by an opening/closing mechanism of the camera. Thus, the film is fed smoothly without any load imposed thereon. When the film is being fed or rewound with the interceptive door open, the film cartridge chamber in the camera in which the film cartridge is loaded must be light tight.
On the other hand, cameras compatible with the novel camera system are designed to reliably hold a film cartridge of the foregoing type and to smoothly feed the film. Correspondingly, the foregoing type of film cartridge is designed to be loaded in a film cartridge chamber in a camera body. Moreover, the above-mentioned types of cameras usually have a film cartridge loader that assists in taking out the film cartridge loaded in the film cartridge chamber.
Various proposals directed to the film cartridge loader have been made in the past and are used in practice.
For example, a camera disclosed in Japanese Unexamined Patent Publication No. 6-301092 has a lid switch and a cartridge switch. The lid switch detects the state of a lid member which is movable for opening or closing a loading opening of a film cartridge chamber. The cartridge switch detects whether or not a film cartridge is fully loaded in the film cartridge chamber. When the cartridge switch has not detected a film cartridge to be loaded in the film cartridge chamber, further actions such as initial film thrusting will not be carried out. This is true even if it is confirmed by the lid switch that the lid member has been closed.
In other words, when it is confirmed by the cartridge switch that a film cartridge has been loaded in the film cartridge chamber, the interceptive door of the film cartridge is opened. Subsequently, actions are performed for feeding the rolled film stowed in the cartridge (initial thrusting actions).
When no film cartridge is loaded in the film cartridge chamber, the actions for feeding a film are not carried out. This feature ensures that unnecessary power will not be consumed.
Moreover, a camera disclosed in Japanese Unexamined Patent Publication No. 8-286269 has an ejecting and indicating member and a switch member. The ejecting and indicating member has the capability to eject a film cartridge loaded in a film cartridge chamber and to indicate a film cartridge-loading state. The switch member is turned on or off responsively to a change in the position of the ejecting and indicating member. The loading state can be discerned externally to see if a film cartridge has been loaded in the film cartridge chamber. Moreover, a signal is generated when the loading of a film cartridge is completed.
This provides the advantage that the loading state can be sensed reliably as to whether a film cartridge has been loaded in the film cartridge chamber.
Furthermore, a film cartridge loading mechanism is described in Japanese Unexamined Patent Publication No. 2-248940. In the disclosed film cartridge loading mechanism, when a film cartridge has been fully loaded in the film cartridge chamber of a camera, if the lid member is closed, the interceptive door of the film cartridge is opened. Using the lid member, a loading opening of the chamber is opened or closed.
In this case, after the actions for closing the lid member are completed, the interceptive door of the film cartridge is opened. The interior of the film cartridge can therefore be reliably protected from light.
According to the camera disclosed in Japanese Unexamined Patent Publication No. 6-301092, when it is confirmed by the cartridge switch that a film cartridge has been loaded in the film cartridge chamber, film feeding actions are performed. The film feeding actions are performed irrespective of the state of the interceptive door of the film cartridge. For example, the interceptive door of the film cartridge may not be fully opened for reasons deriving from failure or the like. Even in this case, the camera may presumably attempt to carry out initial film thrusting actions. In this case, the film may not be able to be fed from the film cartridge, or smooth feeding maybe hindered. Eventually, the camera may malfunction.
Moreover, the camera disclosed in Japanese Unexamined Patent Publication No. 8-286269 is intended to make it possible to externally discern whether a film cartridge has been loaded in the film cartridge chamber. Even when it is confirmed that a film cartridge has been loaded in the film cartridge chamber, no mention is made of subsequent actions a camera should perform. Additionally, the interceptive door of the loaded film cartridge is not described. The presence or absence of a film cartridge and any relationship of the disclosed invention to actions for opening or closing the interceptive door are also not described.
According to the camera disclosed in Japanese Unexamined Patent Publication No. 2-248940, the mechanism for opening the interceptive door of a film cartridge is actuated responsively to actions for closing the lid member. In this reference, the mechanism is actuated irrespective of whether a film cartridge is present in the film cartridge chamber (loading state). In other words, even when no film cartridge is loaded in the film cartridge chamber, if the lid member is closed, the mechanism for opening the interceptive door is actuated. This poses a problem in that unnecessary actions are carried out which eventually wastes power.
Moreover, the film cartridge loading mechanism described in the patent publication mechanically opens or closes the interceptive door of a film cartridge responsively to actions performed for loading the film cartridge in the film cartridge chamber. No mention is made, however, of the inclusion of switches or the like, or of electrical control of relevant series of actions.